The invention relates to an alloy used for a surface layer of a sliding material and more specifically relates to an alloy used as a surface layer of sliding material for automobile, ship, various electric equipments, OA apparatus, agricultural machinery, machine tool, food machinery, and other general industrial machinery. This invention also relates to the sliding material comprising the alloy and the manufacturing method for the sliding material.
The word "sliding material" is intended herein to mean such material as is used for a sliding part of the plane bearing and the like.
For such overlay alloys and the sliding materials there have been conventionally used such alloys as Pb--Sn alloy, Pb--In alloy, Pb--Sn--Cu alloy and Pb--Sn--In alloy and sliding materials having those alloys as a surface layer, those alloys and sliding materials being, for example, shown in "Materials for sliding bearing" by Kazuyuki Morita, Engineer, September 1967, page 44; "Recent trend of materials used for sliding bearing" by the same author, Engineer, April '70, pp 90; Japanese Examined Patent Publication No. 42128/1977; and U.S. Pat. No. 2,605,149. Japanese Examined Patent Publication No. 9635/1982 discloses a technique for making overlay alloy wherein an electroplating method having two steps of plating and a step of heat diffusion are utilized. Because of recent remarkable progress concerning automotive internal combustion engine and other industrial machinery in which higher speed and higher load become possible, conventional sliding materials for sliding parts and the like used for such machinery have caused, when constituted by the above-mentioned conventional overlay alloys, several problems including a shorter service life of bearing experienced particularly under operational conditions of high speed and high load due to insufficient lubricant film which in turn deteriorates wear resisting property, fatigue resisting property and corrosion resistance etc. Furthermore, since in a case of sliding bearing so-called cavitation erosion is inherent in which the erosion of the surface layer of a sliding bearing is caused in lubricant oil, it has also become necessary to prevent or minimize damages caused in the sliding bearing due to the cavitation erosion. Conventioinal overlay alloys such as Pb--Sn alloy, Pb--In alloy and Pb--Sn--In alloy have been not preferred due to large degree of cavitation erosion. In view of this fact, it has been desired in this technical field to obtain a sliding material having a cavitation-erosion resisting property improved in the same degree as in conventional Pb--Sn--Cu overlay alloy.